BACKGROUND: Dietary fiber is an integral part of a healthy diet, but questions remain about the mechanisms that underlie effects and the causal contributions of the gut microbiota. Here, we performed a 6-week exploratory trial in adults with excess weight (BMI: 25-35 kg/m 2) to compare the effects of a high-dose (females: 25 g/day; males: 35 g/day) supplement of fermentable corn bran arabinoxylan (AX; n = 15) with that of microbiota-non-accessible microcrystalline cellulose (MCC; n = 16). Obesity-related surrogate endpoints and biomarkers of host-microbiome interactions implicated in the pathophysiology of obesity (trimethylamine N-oxide, gut hormones, cytokines, and measures of intestinal barrier integrity) were assessed. We then determined whether clinical outcomes could be predicted by fecal microbiota features or mechanistic biomarkers.
RESULTS: AX enhanced satiety after a meal and decreased homeostatic model assessment of insulin resistance (HOMA-IR), while MCC reduced tumor necrosis factor-α and fecal calprotectin. Machine learning models determined that effects on satiety could be predicted by fecal bacterial taxa that utilized AX, as identified by bioorthogonal non-canonical amino acid tagging. Reductions in HOMA-IR and calprotectin were associated with shifts in fecal bile acids, but correlations were negative, suggesting that the benefits of fiber may not be mediated by their effects on bile acid pools. Biomarkers of host-microbiome interactions often linked to bacterial metabolites derived from fiber fermentation (short-chain fatty acids) were not affected by AX supplementation when compared to non-accessible MCC.
CONCLUSION: This study demonstrates the efficacy of purified dietary fibers when used as supplements and suggests that satietogenic effects of AX may be linked to bacterial taxa that ferment the fiber or utilize breakdown products. Other effects are likely microbiome independent. The findings provide a basis for fiber-type specific therapeutic applications and their personalization.
TRIAL REGISTRATION: Clinicaltrials.gov, NCT02322112 , registered on July 3, 2015. Video Abstract.
Bibliographical noteFunding Information:
We thank AgriFiber Solutions LLC (Illinois, USA) for providing AGRIFIBER SFC, and Blanver Farmoquimica LTDA (São Paulo, Brazil) for providing MICROCEL MC-12. We also thank Petra Pjevac, Jasmin Schwarz, and Gudrun Kohl from the Joint Microbiome Facility (Vienna, Austria) for supporting the ex vivo microbiota analysis.
This study was co-funded by a joint European Research Area and Joint Programming Initiative-A Healthy Diet for a Healthy Life (ERA-HDHL) grant (Biomarkers for Nutrition and Health; The FiberTAG Project; www.healthydietforhealthylife.eu/ ) with specific contributions from the Canadian Institutes of Health Research (RN-298871-372173). The ex vivo microbiota analysis was supported by the European Research Council (Starting Grant: FunKeyGut 741623). ECD acknowledges support from the Queen Elizabeth II Graduate Scholarship, Elizabeth Russell MacEachran Scholarship, and Anthony Fellowship in Human Nutrition. JW is funded in part by a Science Foundation Ireland Centre grant to APC Microbiome Ireland (APC/SFI/12/RC/2273_P2) and a Science Foundation Ireland Professorship (19/RP/6853). The funding sources had no role in study design, data collection and analysis, decision to publish, or manuscript preparation.
© 2022, The Author(s).
- Dietary fiber
- Gut microbiota
- Insulin resistance
- Bile Acids and Salts/analysis
- Leukocyte L1 Antigen Complex/analysis
- Gastrointestinal Microbiome/physiology
- Dietary Fiber
PubMed: MeSH publication types
- Clinical Trial
- Research Support, Non-U.S. Gov't
- Video-Audio Media
- Journal Article